Friday, January 31, 2020

Tower Cranes Essay Example for Free

Tower Cranes Essay Force Force can be defined as that which causes a mass to accelerate. Force has common units of pounds force (lbs) or Newtons ? Acceleration (F=MÂ ·A). In other words 1 Newton is the force required to accelerate 1 kilogram by 1 m/sec2, or 1 pound force is the force required to accelerate 1 slug by 1 foot/ sec2. You will notice that the imperial unit for force is pounds force and not just pounds. There is a common inaccuracy in our language that is only really important when talking about physics. The word weight truly refers to a force – this is why your weight on the moon is not the same as your weight on earth. To fully understand this we need to dissect the mathematical meaning behind the force term. Two components go into calculating a force; the first is mass, the second is acceleration. What is mass? Mass is the amount of stuff present in a given sample, lets say a person. A person’s mass will be the same whether on earth or the moon – in both places that person is made up of the same amount of stuff. Mass has two common units; kilograms (kg) and slugs. So a person might have a mass of 70 kg or 4. 78 slugs. For the example of weight, or the downward static force exerted by an object, the acceleration of interest is the acceleration due to gravity. The acceleration due to gravity can be defined as the pull one object exerts on another. For this pull to be felt, one of the objects has to be extremely massive. For most people the most massive object they will encounter is the earth. The acceleration due to gravity on the earth is 9. meters/sec2 or 32. 2 feet/sec2. So a person on earth might weigh (70kg x 9. 8m/sec2) = 686 Newtons or (4. 78 slugs x 32. 2 feet/sec2) = 154 lbs. On the moon the same person will weigh (70kg x 1. 62 m/sec2) = 113 Newtons or (4. 78 slugs x 5. 32 ft/ sec2) = 25 lbs. So when a person says they weigh 154 lbs they are being true to physics, but when they say they weigh 154 kg, they’re actually referring to their mass. As a further twist, it’s also interesting to note that the acceleration due to gravity changes with altitude. So your weight at sea level will be slightly different that your weight at the top of a mountain (Newton’s law of gravitation Fg = G ? gravitational constant). ? kg ? m ? . The equation used to mathematically define force is Force = Mass x 2 ? ? sec ? m1 ? m2 , where G is the r2 Stress Stress is defined as force per unit area and has the common units of Pounds force per Square Inch (psi) or Pascals (Pa) (a Pascal is a Newton per square meter or kg/m sec2). In construction there are five basic types of stress which concern engineers. These are bending, tensile, compressive, shear, and torsional stress (see picture below). For the purpose of building Popsicle stick bridges we are really only interested in bending, compression, and tensile stresses. When we take a close look at bending we’ll see that it is just a combination of tensile and compressive stresses. Of these three types of stress tensile is perhaps the easiest to measure. As a result engineers will take samples of material and, using special machines, subject them to higher and higher tensile loads until they break. By dividing the force at which the sample breaks by the cross sectional area of the sample the materials Ultimate Tensile Stress (UTS) can be determined. The ultimate tensile stress is given the symbol ? (Greek letter sigma), and essentially represents the strength of a material. For comparisons sake a sample of plain carbon steel might have a UTS of 50,000 psi, while pine (which is what Popsicle sticks are made of) might have a UTS of 1,000 psi. It is important to recognize that UTS is not the only important consideration when selecting a material, but material selection is a bit outside the scope of this summary. Let’s take a closer look at tension and compression. Tension is the stress an element experiences when exposed to a pulling force. To get a feeling for tension think about a piece of string. String can only experience tension; it is not able to resist pushing or bending. Compression is the opposite of tension; it’s the stress an element experiences when exposed to a pushing force. Sand is an example of a substance which can only experience compression. A column of sand can support a large load, but is unable to resist any pulling force. As most materials have different tensile and compressive loading potentials, it is important to know what sort of forces will be exerted on every member in a building or bridge. Bending combines both tensile and compressive forces in a single element. To demonstrate this, take a look at the picture below. It’s pretty obvious from this picture that bending puts one face into tension while the other is in compression. It also logically follows from this conclusion that at some point between the two faces there must be a point where there is no tension or compression. This point is called the neutral axis. The mass of material above and below the neutral axis will always be equal. So in a symmetrical member the neutral axis will be along the midline, but will not necessarily be along the midline in an irregularly shaped member. This simple concept of leverage can be used to explain several more complex concepts in structural engineering. The first is why it’s easier to break a Popsicle stick when it’s bent on its flat side as opposed to its edge. To explain this we have to explain the concept of leverage. This one is pretty simple and can easily be demonstrated by the classroom door. Leverage (also called moment or torque) occurs when a force is applied to an object which can rotate about a pivot point. In the case of the classroom door the pivot is the hinge and the force applied comes from the person wanting to open the door. In the case of bending a Popsicle stick the pivot is the neutral axis and the force we’re concerned with is the tension or compression on the outside faces. Moment is calculated by multiplying the force applied by the distance from the point of force application to the pivot. If you increase the applied force, or the distance from the pivot point, the moment increases. That’s why door handles are put as far from the hinge as possible – we make the distance from the point of force application to the pivot point as large as possible, that way a small applied force will create a large moment. So the Popsicle stick is harder to break when bent on edge because we’ve increased the distance from the neutral axis to the point of maximum force. Explain the difference between tensile, bending, and compressive forces with examples of the equations used to calculate each. Explain truss elements and why they are a superior way of building a bridge. Sample FEM output for simple bridge design o Calculate the amount of popsicle sticks required to make a simple beam with the same strength as a truss element. Hints on building a strong bridge o Truss o Strength comes from the Popsicle sticks, not the glue – but well glued joints are a must. Additional information: http://andrew. triumf. ca/andrew/popsicle-bridge/ http://www. eir. ca/resources/presentations/Bridges%20-%20By%20Doug%20Knight. doc

Thursday, January 23, 2020

The Language Barrier for Puerto Ricans :: Caribbean History Language Essays

The Language Barrier for Puerto Ricans "Pollito, Chicken Gallina, Hen Lapiz, Pencil y Pluma, Pen. Ventana, Window Puerta, Door Maestra, Teacher y Piso, Floor I sing in English, I sing in Spanish, so all my friends can understand." The issue of language is central to the Puerto Rican experience in the United States. Living in a land where the dominant language is English, this Spanish speaking population is involved in a historical struggle to overcome the language barrier. Among other things, their unfamiliarity with the English language has been a major obstacle to the progression of the Puerto Rican people as a whole. The inability of Puerto Rican’s to speak English has served to exacerbate their situation in the United States; a situation where they are already met with discrimination simply for being foreigners. In the classrooms, Puerto Ricans have met only minimal success, largely due to their inability to properly communicate with teachers and peers. In the workplace, Puerto Ricans have historically been given only menial jobs. Due to their inability to speak English, many Puerto Ricans are unable to conduct themselves in job interviews, fill out application forms, or communicate with customers. As a result, the more competitive job fields show an under-representation of Puerto Ricans. Finally, many Puerto Ricans find it difficult to conduct themselves in places such as hospitals, courtrooms, and post offices due to the language barrier. This leads to the issue of bilingualism. Should the mainstream environment of the schools and workplace of America consist of two languages? T his issue has been debated for many years. This paper focuses on the issue of bilingualism in Hartford, while also looking at the context under which Puerto Ricans in Hartford find themselves in their current situation. These issues are examined with the use of historical fact, along with information and sentiments on current events in the Hartford community concerning the issue of bilingualism and culture. Puerto Rican History In the year 1508, the Spanish arrived in Puerto Rico and began the Spanish colonization of the island. At this time, the island was called Boriquen and was inhabited by an Indian tribe called Tainos. During this process, the Spanish established their way of life on the island while decimating the Tainos in terms of population due to Spanish disease, slavery and oppression.

Wednesday, January 15, 2020

How Groups Can Influence People in Positive and Negative Ways Essay

Groups influence people in positive and negative ways. Looking at research and studies we will see how the roles we play in groups can influence our behaviour. We will see how groups we gravitate to help raise our self-esteem and give us a sense of belonging but at the same time how conflict is created with other groups. Groups we belong to help to give us a sense of identity but we will see how we can lose this as we conform to group behaviour and the impact this can have. Finally, we will look at Kondo’s research and how changing cultures slowly changed her identity and how this affected her on her journey emphasising her positive and negative influences. As we grow we will have many social identities which influence the groups we belong to. These groups can range from friends to family and further out to groups like nationality and ethnicity. Within these groups we have different roles to play which influence our behaviour. A controversial experiment by Zimbardo (1971) (Spoors et al.) shows how a groups of males were separated into two groups of guards and prisoners in a make shift prison. After six days of a two week experiment it was stopped. The guards became abusive while the prisoners showed signs of emotional disturbance. Lots of factors could have influenced the participant’s behaviour but this experiment shows us the effect that roles have on us in a group and how quick we are to adapt to them. We see how an individual can turn abusive and also how individuals can be walked over an abused. Regarding Zimbardo’s experiment we can identify two groups. Psychologists call these our ‘in’ and ‘out’ groups. Evidence suggests our ‘in group’ raises our self-esteem, we gain a sense of belonging, identification and a sense of status. Our ‘in group’ also gives us an opportunity to compare with our ‘out group’ this can create conflict as an us and them divide is formed. Positively we show favour to our ‘in group’ and negatively we discriminate against our ‘out group’. Tajfel et al. (1971) (Spoors et al.) showed this when he assigned teenage boys to a ‘virtual group’ that did not exist. The boys still showed favouritism to their ‘in group’. We see this behaviour in an experiment conducted by Sherif et al. (1961) (Spoors et al.). He set two sets of boys in a summer camp into groups. Separately the groups interacted, group norms were followed, they joked and had secret codes. The groups were set against each other in competition and within their own groups co-operation and loyalty were heightened but hostility, aggression and prejudiced was seen between the groups. Observing Sherif’s study we see positively how group members found a sense of belonging in their own group and how loyalty and co-operation were heightened by competition. Negatively we see their behaviour changing when clashing against their ‘out group’ becoming hostile, aggressive and prejudiced. Prejudism against our ‘out group’ bolsters self-esteem as it allows us to see other groups as inferior. We feel safe and part of our ‘in group’ but through group pressure we may conform to the rest of the group and the sense of identity we gained we could start to lose as we become more influenced by the rest of the group. Asch (1951) (Spoors et al.) looked at this and conducted an experiment on conformity. Participants had to match two lines out of a group of four that were similar in length with a group of other people. Participants conformed with the group who deliberately gave wrong answers. This was repeated and seventy five per cent of participants gave a wrong answer at least once. Asch’s experiment shows the influence of group pressure. Negatively this influence can have disastrous implications. Spoors et al. (2011) use the example of the ‘Heavens Gate’ cult. Thirty nine of their members committed suicide believing their souls would be transported to a spaceship behind Hale Bop comet. Psychological factors need to be recognised but would they have acted this way left to their own devices? Positively Asch’s experiment shows us how we like to feel part of a group and not left out. Society would be chaos if people did not conform to some degree. Just going to the cinema and being quiet we are conforming to the silence so others are not offended. Cultures will have an influence on conformity as Collectivist cultures emphasise groups more than Individualist cultures so all depending where we live in the world cultures influence our behaviour in groups. As our behaviour changes so will our own social identities and this can finally lead us onto research by Dorinne Kondo (1990) (Spoors et al.) Dorinne Kondo was a Japanese American raised in the U.S.A. She moved to Japan to take part in research involving participant-observational study moving in with a Japanese family. Over time she found her American identity diminishing and her new identity flourishing encountering both positive and negative influences on her journey. Negatively she describes being confronted with bewilderment, embarrassment even anger on her linguistical mistakes and when conforming wrongly to Japanese customs also when ‘proper’ behaviour meant she had to behave subserviently. She describes her conflicts surrounding expectations of gender especially her role as a young woman. Positively she describes being left with a warm positive feeling to her live in family when being affirmed for behaving with proper Japanese etiquette. After time she found herself losing her American identity. In her tea ceremony class she explains her awkward, exaggerated western movements had been replaced with Japanese grace. Kondo’s research demonstrates the positive and negative influences we encounter in different cultures and how they can change us as a person as our identities evolve. We have seen how groups can influence people in both positive and negative ways. Zimbardo’s prison experiment shows us how quick we take up roles in a group and the extent to which we act out these roles. Sherif’s summer camp study shows how we look for a sense of belonging and to raise our self-esteem in a group but how we discriminate when conflict is created. These same groups who we look to for affirmation can influence us so greatly we will make the wrong decisions. We have also seen from research how different cultures can influence our positive and negative behaviour in groups and the impact this has on us as our identities evolve.

Tuesday, January 7, 2020

The Amazing and Horrifying Story of Kurt Gerstein

Anti-Nazi Kurt Gerstein (1905-1945) never intended to be a witness to the Nazi murder of the Jews. He joined the SS to try to find out what happened to his sister-in-law, who had mysteriously died in a mental institution. Gerstein was so successful in his infiltration of the SS that he was placed in a position to witness gassings at Belzec. Gerstein then told everyone he could think of about what he saw and yet no action was taken. Some wonder if Gerstein did enough. Kurt Gerstein Kurt Gerstein was born on August 11, 1905, in Mà ¼nster, Germany. Growing up as a young boy in Germany during the First World War and the following tumultuous years, Gerstein did not escape the pressures of his time. He was taught by his father to follow orders without question; he agreed with the growing patriotic fervor that espoused German nationalism, and he was not immune to the strengthening anti-Semitic feelings of the inter-war period. Thus he joined the Nazi Party on May 2, 1933. However, Gerstein found that much of the National Socialist (Nazi) dogma went against his strong Christian beliefs. Turning Anti-Nazi While attending college, Gerstein became very involved in Christian youth groups. Even after graduating in 1931 as a mining engineer, Gerstein remained very active in the youth groups, especially the Federation of German Bible Circles (until it was disbanded in 1934). On January 30, 1935, Gerstein attended an anti-Christian play, Wittekind at the Municipal Theater in Hagen. Though he sat amongst numerous Nazi members, at one point in the play he stood up and shouted, This is unheard of! We shall not allow our faith to be publicly mocked without protest!1 For this statement, he was given a black eye and had several teeth knocked out.2 On September 26, 1936, Gerstein was arrested and imprisoned for anti-Nazi activities. He had been arrested for attaching anti-Nazi letters to invitations sent out to invitees of the German Miners Association.3 When Gersteins house was searched, additional anti-Nazi letters, issued by the Confessional Church, were found ready to be mailed along with 7,000 addressed envelopes.4 After the arrest, Gerstein was officially excluded from the Nazi Party. Also, after six weeks of imprisonment, he was released only to find that he had lost his job in the mines. Arrested Again Not able to get a job, Gerstein went back to school. He began to study theology at Tà ¼bingen but soon transferred to the Protestant Missions Institute to study medicine. After a two-year engagement, Gerstein married Elfriede Bensch, a pastors daughter, on August 31, 1937. Even though Gerstein had already suffered exclusion from the Nazi Party as a warning against his anti-Nazi activities, he soon resumed his distribution of such documents. On July 14, 1938, Gerstein was again arrested. This time, he was transferred to the Welzheim concentration camp where he became extremely depressed. He wrote, Several times I came within an ace of hanging myself of putting an end to my life in some other way because I hadnt the faintest idea if, or when, I should ever be released from that concentration camp.5 On June 22, 1939, after Gersteins release from the camp, the Nazi Party took even more drastic action against him regarding his status in the Party - they officially dismissed him. Gerstein Joins the SS In the beginning of 1941, Gersteins sister-in-law, Bertha Ebeling, died mysteriously at the Hadamar mental institution. Gerstein was shocked by her death and became determined to infiltrate the Third Reich to find out the truth about the numerous deaths at Hadamar and similar institutions. On March 10, 1941, a year and a half into the Second World War, Gerstein joined the Waffen SS. He was soon placed in the medical services hygiene section where he succeeded in inventing water filters for German troops - to his superiors delight. Gerstein had been dismissed from the Nazi Party, thus should not have been able to hold any Party position, especially not become part of the Nazi elite. For a year and a half, the anti-Nazi Gersteins entry into the Waffen SS went unnoticed by those that had dismissed him. In November 1941, at a funeral for Gersteins brother, a member of the Nazi court that had dismissed Gerstein saw him in uniform. Although information about his past was passed on to Gersteins superiors, his technical and medical skills - proven by the working water filter - made him too valuable to dismiss, Gerstein was thus allowed to stay at his post. Zyklon B Three months later, in January 1942, Gerstein was appointed the head of the Technical Disinfection Department of the Waffen SS where he worked with various toxic gases, including Zyklon B. On June 8, 1942, while the head of the Technical Disinfection Department, Gerstein was visited by SS Sturmbannfà ¼hrer Rolf Gà ¼nther of the Reich Security Main Office. Gà ¼nther ordered Gerstein to deliver 220 pounds of Zyklon B to a location known only to the driver of the truck. Gersteins main task was to determine the feasibility of changing the Aktion Reinhard gas chambers from carbon monoxide to Zyklon B. In August 1942, after having collected the  Zyklon B  from a factory in Kolin (near Prague, Czech Republic), Gerstein was taken to  Majdanek, Belzec, and  Treblinka. Belzec Gerstein arrived at Belzec on August 19, 1942, where he witnessed the entire process of gassing a trainload of Jews. After the unloading of 45 train cars stuffed with 6,700 people, those that were still alive were marched, completely naked, and told that no harm would come to them.  After the gas chambers were filled: Unterscharfà ¼hrer Hackenholt was making great efforts to get the engine running. But it doesnt go. Captain Wirth comes up. I can see he is afraid because I am present at a disaster. Yes, I see it all and I wait. My stopwatch showed it all, 50 minutes, 70 minutes, and the diesel did not start. The people wait inside the gas chambers. In vain. They can be heard weeping, like in the synagogue, says Professor Pfannenstiel, his eyes glued to a window in the wooden door. Furious, Captain Wirth lashes the Ukrainian assisting Hackenholt twelve, thirteen times, in the face. After 2 hours and 49 minutes - the stopwatch recorded it all - the diesel started. Up to that moment, the people shut up in those four crowded chambers were still alive, four times 750 persons in four times 45 cubic meters. Another 25 minutes elapsed. Many were already dead, that could be seen through the small window because an electric lamp inside lit up the chamber for a few moments. After 28 minutes, only a few were still alive. Finally, after 32 minutes, all were dead. 6 Gerstein was then shown the processing of the dead: Dentists hammered out gold teeth, bridges and crowns. In the midst of them stood Captain Wirth. He was in his element, and showing me a large can full of teeth, he said: See for yourself the weight of that gold! Its only from yesterday and the day before. You cant imagine what we find every day - dollars, diamonds, gold. Youll see for yourself! 7 Telling the World Gerstein was shocked by what he had witnessed. Yet, he realized that as a witness, his position was unique. I was one of the handful of people who had seen every corner of the establishment, and certainly the only one to have visited it as an enemy of this gang of murderers. 8 He buried the Zyklon B canisters that he was supposed to deliver to the death camps. He was shaken by what he had seen. He wanted to expose what he knew to the world so that they could stop it. On the train back to Berlin, Gerstein met Baron Gà ¶ran von Otter, a Swedish diplomat. Gerstein told von Otter all he had seen. As von Otter relates the conversation: It was hard to get Gerstein to keep his voice down. We stood there together, all night, some six hours or maybe eight. And again and again, Gerstein kept on recalling what he had seen. He sobbed and hid his face in his hands. 9 Von Otter made a detailed report of his conversation with Gerstein and sent it to his superiors. Nothing happened. Gerstein continued to tell people what he had seen. He tried to contact the Legation of the Holy See but was denied access because he was a soldier.10 [T]aking my life in my hands every moment, I continued to inform hundreds of people of these horrible massacres. Among them were the Niemà ¶ller family; Dr. Hochstrasser, the press attachà © at the Swiss Legation in Berlin; Dr. Winter, the coadjutor of the Catholic Bishop of Berlin - so that he could transmit my information to the Bishop and to the Pope; Dr. Dibelius [bishop of the Confessing Church], and many others. In this way, thousands of people were informed by me.11 As months continued to pass and still the Allies had done nothing to stop the extermination, Gerstein became increasingly frantic. [H]e behaved in a strangely reckless manner, needlessly risking his life every time he spoke of the extermination camps to persons he scarcely knew, who were in no position to help, but might easily have been subjected to torture and interrogation. . .  12 Suicide or Murder On April 22, 1945, near the end of the war, Gerstein contacted the Allies. After telling his story and showing his documents, Gerstein was kept in honorable captivity in Rottweil - this meant he was lodged at Hotel Mohren and just had to report to the French gendarmerie once a day.13 It was here that Gerstein wrote down his experiences - both in French and German. At this time, Gerstein seemed optimistic and confident. In a letter, Gerstein wrote: After twelve years of unremitting struggle, and in particular after the last four years of my extremely dangerous and exhausting activity and the many horrors I have lived through, I should like to recuperate with my family in Tà ¼bingen. 14 On May 26, 1945, Gerstein was soon transferred to Constance, Germany and then to Paris, France in early June. In Paris, the French did not treat Gerstein differently than the other war prisoners. He was taken to the Cherche-Midi military prison on July 5, 1945. The conditions there were terrible. On the afternoon of July 25, 1945, Kurt Gerstein was found dead in his cell, hung with part of his blanket. Though it was apparently a suicide, there is still some question if it was perhaps murder, possibly committed by other German prisoners who did not want Gerstein to talk. Gerstein was buried in the Thiais cemetery under the name Gastein. But even that was temporary, for his grave was within a section of the cemetery that was razed in 1956. Tainted In 1950, a final blow was given to Gerstein - a denazification court posthumously condemned him. After his experiences in the Belzec camp, he might have been expected to resist, with all the strength at his command, being made the tool of an organized mass murder. The court is of the opinion that the accused did not exhaust all the possibilities open to him and that he could have found other ways and means of holding aloof from the operation. . . .Accordingly, taking into account the extenuating circumstances noted . . . the court has not included the accused among the main criminals but has placed him among the tainted.15 It was not until January 20, 1965, that Kurt Gerstein was cleared of all charges, by the Premier of Baden-Wà ¼rttemberg. End Notes Saul Friedlà ¤nder,  Kurt Gerstein: The Ambiguity of Good  (New York: Alfred A. Knopf, 1969) 37.Friedlà ¤nder,  Gerstein  37.Friedlà ¤nder,  Gerstein  43.Friedlà ¤nder,  Gerstein  44.Letter by Kurt Gerstein to relatives in the United States as quoted in Friedlà ¤nder,  Gerstein  61.Report by Kurt Gerstein as quoted in Yitzhak Arad,  Belzec, Sobibor, Treblinka: The Operation Reinhard Death Camps  (Indianapolis: Indiana University Press, 1987)  102.Report by Kurt Gerstein as quoted in Arad,  Belzec  102.Friedlà ¤nder,  Gerstein  109.Friedlà ¤nder,  Gerstein  124.Report by Kurt Gerstein as quoted in Friedlà ¤nder,  Gerstein  128.Report by Kurt Gerstein as quoted in Friedlà ¤nder,  Gerstein  128-129.Martin Niemà ¶ller as quoted in Friedlà ¤nder,  Gerstein  179.Friedlà ¤nder,  Gerstein  211-212.Letter by Kurt Gerstein as quoted in Friedlà ¤nder,  Gerstein  215-216.Verdict of the Tà ¼bingen Denazification Court, August 17, 1950 as quoted in Friedlà ¤nder,  Gerstein  225-226. Bibliography Arad, Yitzhak.  Belzec, Sobibor, Treblinka: The Operation Reinhard Death Camps. Indianapolis: Indiana University Press, 1987.Friedlà ¤nder, Saul.  Kurt Gerstein: The Ambiguity of Good. New York: Alfred A Knopf, 1969.Kochan, Lionel. Kurt Gerstein.  Encyclopedia of the Holocaust. Ed. Israel Gutman. New York: Macmillan Library Reference USA, 1990.